This invention relates, in general, to internal combustion engines, and specifically, to intake and exhaust valve systems for internal combustion engines. 2. State of the Art
An internal combustion, four-stroke engine contains a cylinder head, a plurality of cylinders each having a piston reciprocally mounted therein, and intake and exhaust valves associated with each cylinder. The intake and exhaust valves control the flow of fuel into the combustion chamber of the cylinder as well as the exhaust of combustion gases from the cylinder on a time basis.
Timing is achieved by the use of one or more cams, valve lifters, push rods, rocker arms, rocker arm shafts, valve guides and a cam timing chain or belt. These intake and exhaust valve components form a complex mechanical system which contains a large number of individual parts. The mechanical system also has considerable weight which is a disadvantage when high fuel economies are desired. Further, due to the numerous components, such mechanical systems have a high manufacturing cost and require continuous maintenance and repair, as well as a considerable number of spare parts.
Certain attempts to overcome these problems and reduce the number of components in the intake and exhaust valve train have utilized a single rotary shaft in which a series of ports or bores are formed at various angles along the length of the shaft. Two of the ports in the shaft are disposed in fluid flow communication with each cylinder of the engine and provide timed intake and exhaust of fuel and combustion gases to and from the cylinder as the shaft rotates. However, the rotation of such rotary shafts are still effected by mechanical means including belts, pulleys, etc., which are connected to the engine crankshaft.
Thus, it would be desirable to provide an intake and exhaust valve system for an internal combustion engine which overcomes the aforementioned problems associated with previously devised intake and exhaust structure. It would be desirable to provide an intake and exhaust valve system for an internal combustion engine which has a minimum number of individual components for a low manufacturing cost, low weight, low volume or space requirements, and high efficiency. It would also be desirable to provide an intake and exhaust system for an internal combustion engine in which valve timing is effected solely by electrical means, rather than mechanical means.